Son debuted in 1997 with the LG Twins, going 7 for 22 with a walk and 2 doubles. In 1998, he hit .233/.313/.283 in 60 AB. During 1999, he was 4 for 35 with no walks or extra-base hits. In 2000, Son hit .238/.294/.302 in 63 AB. The LG infielder hit .250/.297/.383 in 2001. In 2002, he batted .214/.272/.297 as a starter.

Son hit .189/.265/.203 in 74 AB for the 2003 Twins. Son played for South Korea in the 2003 Baseball World Cup, hitting .333/.400/.528 with 8 runs in 9 games as their main shortstop. Eduardo Paret beat him out for All-Tournament honors at shortstop.

Son moved to the KIA Tigers in 2004 and hit .271/.311/.455 with 13 home runs in 303 AB; his previous home run high had been five. In 2005, Son hit .236/.344/.424 with 11 HR in 316 AB. During 2006, he hit .264/.303/.352. In 2007, the KIA infielder slumped to .217/.283/.326 in 102 games. He went 3 for 10 with two doubles as a backup 2B for South Korea in the 2007 Baseball World Cup.